This invention relates to a preloading apparatus for an elongate prop such as is used in underground mines to provide a yielding support for a hanging wall relative to a footwall.
A large proportion of the elongate props used underground in mines comprise or consist of a timber pole. In use, the pole is cut to length and the prop is arranged upright between the hanging and foot walls. The prop is then wedged into position between the hanging and foot walls by means of separate timber wedges which are hammered into position between the upper end of the prop and the hanging wall. This wedging of the prop gives it stability to prevent it from falling over when nearby blasting takes place or the prop is impacted by underground personnel or equipment.
In addition to merely wedging the prop in position, however, it would be desirable to apply to it some compressive force such that the prop is immediately ready to take the full compressive load which is imposed thereon when the hanging wall closes on the footwall with passage of time.